Thrombectomy device and methods of use

ABSTRACT

The device disclosed herein is used to the remove a thrombus from the vasculature. It includes an aspiration catheter and a thrombus retrieval device that extends through the lumen of the aspiration catheter. An expandable braided assembly extends over a distal region of the retrieval device, and an activation wire extends through the lumen of the retrieval device to attach to and control the expansion of the braided assembly. Applying tension to the activation wire causes the braided assembly to expand to a diameter of the practitioner&#39;s choosing. For example, the practitioner may apply a first level of tension to the activation wire to deploy the braided assembly to a first diameter and then later change the diameter by applying a different level of tension. The expanded braided assembly contacts the thrombus and is pulled proximally toward the aspiration catheter to assist in thrombus removal.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/185,319, filed Nov. 9, 2018, which claims the benefit of U.S.Provisional Application 62/583,613, filed Nov. 9, 2017. Each of theaforementioned applications is incorporated herein by reference in itsentirety for all purposes.

FIELD

This invention relates to a medical device for the removal of tissuefrom the body. One specific use of this device is removal of blood clots(thrombus) or plaque from arteries or veins.

BACKGROUND

It is often desirable to remove tissue from the body in a minimallyinvasive manner as possible, so as not to damage other tissues. Forexample, removal of tissue (e.g., blood clots) from the vasculature mayimprove patient conditions and quality of life.

Many vascular system problems stem from insufficient blood flow throughblood vessels. One causes of insufficient or irregular blood flow is ablockage within a blood vessel referred to as a blood clot, or thrombus.Thrombi can occur for many reasons, including after a trauma such assurgery, or due to other causes. For example, a large percentage of themore than 1.2 million heart attacks in the United States are caused byblood clots (thrombi) which form within a coronary artery.

When a thrombus forms, it may effectively stop the flow of blood throughthe zone of formation. If the thrombus extends across the interiordiameter of an artery, it may cut off the flow of blood through theartery. If one of the coronary arteries is 100% thrombosed, the flow ofblood is stopped in that artery, resulting in a shortage of oxygencarrying red blood cells, e.g., to supply the muscle (myocardium) of theheart wall. Such a thrombosis is unnecessary to prevent loss of bloodbut can be undesirably triggered within an artery by damage to thearterial wall from atherosclerotic disease. Thus, the underlying diseaseof atherosclerosis may not cause acute oxygen deficiency (ischemia) butcan trigger acute ischemia via induced thrombosis. Similarly, thrombosisof one of the carotid arteries can lead to stroke because ofinsufficient oxygen supply to vital nerve centers in the cranium. Oxygendeficiency reduces or prohibits muscular activity, can cause chest pain(angina pectoris), and can lead to death of myocardium which permanentlydisables the heart to some extent. If the myocardial cell death isextensive, the heart will be unable to pump sufficient blood to supplythe body's life sustaining needs. The extent of ischemia is affected bymany factors, including the existence of collateral blood vessels andflow which can provide the necessary oxygen.

Clinical data indicates that clot removal may be beneficial or evennecessary to improve outcomes. For example, in the peripheralvasculature, inventions and procedures can reduce the need for anamputation by 80 percent. The ultimate goal of any modality to treatthese conditions of the arterial or venous system is to remove theblockage or restore patency, quickly, safely, and cost effectively. Thismay be achieved by thrombus dissolution, fragmentation, thrombusaspiration or a combination of these methods.

Catheter directed thrombectomy and thrombolysis are commonly perceivedto be less traumatic, less likely to decrease the morbidity andmortality associated with conventional surgical techniques. In recentyears, direct administration of chemical lysing agents into the coronaryarteries has shown to be of some benefit to patients who have thrombosedcoronary arteries. In this procedure, a catheter is placed immediatelyin front of the blockage and a drip of streptokinase is positioned to bedirected at the upstream side of the thrombus. Streptokinase is anenzyme which is able in time to dissolve the fibrin molecule. Thisprocedure can take several hours and is not always successful inbreaking up the thrombus. Furthermore, it can lead to downstreamthrombus fragments (emboli) which can lead to blockage of small diameterbranches.

Thrombectomy is a technique for mechanical removal of blood clots in anartery or vein. It refers to physically removing a clot as opposed toemploying chemical lysis to dissolve it. Multiple devices have beenintroduced to break up and remove clot and plaque, but each has its ownshortcomings. Specifically, the existing systems do not provide adequatemethods for breaking up the clot into smaller pieces for subsequentaspiration. Also, they do not provide a method for removing thethrombectomy device over a guidewire and reinserting into the samelocation to complete the procedure. There is a need for an improvedthrombectomy device that is more effective for removing thrombus andplaque from the vascular system.

SUMMARY

The devices and methods disclosed herein provide an improvedthrombectomy device that achieves the objective of more efficient clotremoval via improved intra-arterial geometry with over-the-wirefunctionality. The thrombectomy devices disclosed herein remove thrombiusing braided assemblies that can be expanded to a diameter of thepractitioner's choosing, enabling the practitioner to custom fit thedevice to the particular thrombus during the procedure. Unlikeconventional thrombectomy devices, the diameter of the disclosed braidedassembly can be changed mid-procedure as needed, for example, shouldadditional grip be needed for removal of the thrombus. In someembodiments, multiple braided assemblies can be used to address longerthrombi. Each braided assembly can be separately expanded, such that theindividual assemblies have different diameters during the procedure.

The aspiration catheter includes a proximal end and a distal end. Theretrieval device extends through the lumen of the aspiration catheterand exits at the distal end. The retrieval device includes a proximalregion, a distal region, and a first lumen extending between theproximal and distal regions. At least one braided assembly extends overa distal region of the retrieval device. The at least one braidedassembly includes at least one slidable collar and a braid attached tothe slidable collar. The braid can be one ply or two ply. The braidextends from the slidable collar toward a fixed attachment point thatanchors the braid to the retrieval device. Upon expansion, the braidtakes an elliptical or a spindle shape, having a maximum diameter nearthe center and narrowing as the proximal and distal regions approach thelongitudinal axis of the braid.

At least one activation wire extends through the first lumen of theretrieval device and through an exit point located on the distal region.A distal end of the activation wire is attached to the slidable collar.In some embodiments, the exit point is a portal in a sidewall of theretrieval device. The portal can be positioned beneath the braid of thebraided assembly, for example. In some embodiments, the retrieval deviceincludes a proximally located hypotube and a distally located supporttube that has greater flexibility than the proximal hypotube. The portalcan be defined in a sidewall of the distal support tube, and the braidedassembly can be positioned over the distal support tube. In someembodiments, the distal support tube is attached to the distal end ofthe proximal hypotube.

Applying tension to the activation wire causes the braided assembly toexpand to a diameter of the practitioner's choosing. As such, thebraided assembly can be expanded to a range of expanded outer diametersby varying the level of tension on the activation wire. For example, thebraided assembly is deployable to a first expanded outer diameter byplacing a first level of tension on the activation wire, or to a secondexpanded outer diameter by placing a second level of tension on theactivation wire. The practitioner may apply a first level of tension tothe activation wire to deploy the braided assembly to a first diameterand then later change the diameter by applying a different level oftension. In some embodiments, the first level of tension in theactivation wire is less than the second level of tension in theactivation wire, such that the first expanded outer diameter is themaximum diameter of the braid in a partially expanded configuration, andthe second expanded outer diameter is the maximum diameter of the braidin a fully expanded configuration. The expanded braided assemblycontacts the thrombus and is pulled proximally toward the aspirationcatheter to assist in thrombus removal. The braid has a shape memory ofthe collapsed configuration, so releasing tension in the activation wireallows the braid to relax to back to the collapsed state, for example,as it enters the aspiration catheter during removal.

Some embodiments of the thrombectomy device can further include aguidewire tubing. In some embodiments, the guidewire tubing can beshorter than the retrieval device. The retrieval device extends throughthe first lumen of the guidewire tubing, and the second lumen of theguidewire tubing extends over a guidewire. The fixed point of attachmentof the braided assembly can be located on the guidewire tubing in someembodiments. The guidewire tubing can be shorter than the retrievaldevice in the longitudinal direction in some embodiments.

Some embodiments of the thrombectomy device can include a braidedassembly with multiple braided sections and multiple sliding collars. Inthese embodiments, each additional slidable collar is positioned betweentwo braided sections. Tensioning the activation wire causes at leastpartial expansion of each of the braided sections. The multiple braidedsections can be formed of one continuous braid, or they can be formed ofseparate braids. In some embodiments, the activation wire is attached toone of multiple slidable collars. For example, the activation wire maybe attached to the distal-most slidable collar.

Some embodiments of the thrombectomy device include at least oneadditional braided assembly and at least one additional activation wire.Each additional activation wire is attached to an additional slidablecollar of an additional braided assembly, such that each braidedassembly is separately expandable via an attached activation wire.

Some embodiments of the thrombectomy device include a proximally locatedtensioning element for controlling the activation wire that expands thebraided assembly. The proximal end of the activation wire is attached toa tensioning element, which can be attached to a proximally locatedhandle, for example.

Methods of performing thrombectomy procedures are also disclosed herein.The methods include advancing the distal end of the aspiration catheterthrough the vasculature to an area proximal to a thrombus, and advancingthe distal end of the retrieval device carrying at least one braidedassembly out of the distal end of the aspiration catheter and to aposition distal to the thrombus. A first level of tension is applied tothe activation wire that attaches to the braided assembly. The firstlevel of tension moves the activation wire longitudinally within a lumenof the retrieval device, thereby moving the slidable collar of thebraided assembly longitudinally over an exterior surface of theretrieval device and deploying the braided assembly to a first expandedouter diameter. If desired, a second level of tension, either greater orsmaller than the first level of tension, can be applied to theactivation wire. The second level of tension moves the activation wirelongitudinally within the lumen of the retrieval device, thereby movingthe slidable collar of the braided assembly longitudinally over theexterior surface of the retrieval device and deploying the braidedassembly to a second expanded outer diameter. The distal end of theretrieval device maintains a stationary position as the slidable collarmoves longitudinally over the exterior surface of the retrieval deviceand the braided assembly is expanded to the optimal diameter. In someembodiments, the second level of tension opens the braided assembly to awider second expanded outer diameter to more firmly contact the thrombuswith the braid. The thrombus is pulled toward the aspiration catheterand aspirated into the distal end of the aspiration catheter. In someembodiments, the thrombus is aspirated into the distal end of theaspiration catheter using an external vacuum source.

In some embodiments of the methods, the thrombus can be contacted andpulled using multiple braided sections or multiple braided assemblies.For example, movement of a single slidable collar can cause expansion ofmore than one braided section of a braided assembly. In another example,a proximally positioned braided assembly can collapse from a firstexpanded outer diameter to a narrower second outer diameter as itapproaches the distal end of the aspiration catheter, while a distallypositioned braided assembly can maintain an expanded outer diameter thatis equivalent to or wider than the second outer diameter of theproximally positioned braided assembly.

Some embodiments of the methods can include the use of a guidewire.These methods include advancing the guidewire to a position distal tothe thrombus prior to advancing the distal end of the retrieval device.The retrieval device can extend at least partially through a first lumenof a guidewire tubing, and the method includes advancing the guidewiretubing with the retrieval device over the guidewire. The activation wiremoves longitudinally within the retrieval device, which is in the firstlumen of the guidewire tubing. The guidewire moves longitudinally withina second lumen of the guidewire tubing.

DESCRIPTION OF DRAWINGS

FIG. 1A is a side section view of an embodiment of the thrombectomydevice having a single braided assembly in the collapsed configuration.

FIG. 1B is a side view showing the distal region of retrieval device thethrombectomy device carrying the braided assembly of FIG. 1A. Thebraided assembly is shown in an expanded configuration.

FIG. 1C is a side view showing the distal region of the thrombectomydevice retrieval device of FIG. 1A. The braided assembly is not includedin this view.

FIG. 1D is a cross sectional view of the embodiment of FIG. 1A, takenalong lines A-A of FIG. 1C.

FIG. 2 shows a side view of an embodiment of a handle that can be usedto control expansion and retraction of a braided assembly. FIG. 3A is aside view of a distal region of an additional embodiment of thethrombectomy device in an unexpanded configuration. The embodiment has abraided assembly having multiple braided sections.

FIG. 3B is a side view of the distal region of the embodiment of FIG. 3Ain an expanded configuration.

FIG. 3C is a side view of the distal region of the thromectomy device ofFIG. 3A. The braided assembly is not included in this view.

FIG. 3D shows a cross sectional view taken along line 3D-3D of FIG. 3C.

FIG. 3E shows a cross sectional view taken along line 3E-3E of FIG. 3C.

FIG. 3F shows a cross sectional view taken along line 3F-3F of FIG. 3C.

FIG. 3G shows a cross sectional view taken along line 3G-3G of FIG. 3C.

FIG. 4 shows an additional embodiment of the thrombectomy device havingmultiple expandable braided assemblies.

FIG. 5A shows a side section view of an embodiment of the thrombectomydevice that enables use with a guidewire.

FIG. 5B shows the embodiment of FIG. 5A in an expanded configuration.

FIG. 5C is a cross section of the embodiment of FIGS. 5A and 5B, takenalong line B-B of FIG. 5B.

FIGS. 6A-6F show an example method of using a thrombectomy device.

FIG. 7A shows a perspective view of another embodiment of a handle thatcan be used to control expansion and retraction of a braided assembly.

FIG. 7B shows a bottom up, inside view of the locking slider of thehandle embodiment of FIG. 7A.

FIG. 7C shows a cross section of the locking slider circled in FIG. 7B.

DETAILED DESCRIPTION

The following description of certain examples of the inventive conceptsshould not be used to limit the scope of the claims. Other examples,features, aspects, embodiments, and advantages will become apparent tothose skilled in the art from the following description. As will berealized, the device and/or methods are capable of other different andobvious aspects, all without departing from the spirit of the inventiveconcepts. Accordingly, the drawings and descriptions should be regardedas illustrative in nature and not restrictive.

For purposes of this description, certain aspects, advantages, and novelfeatures of the embodiments of this disclosure are described herein. Thedescribed methods, systems, and apparatus should not be construed aslimiting in any way. Instead, the present disclosure is directed towardall novel and nonobvious features and aspects of the various disclosedembodiments, alone and in various combinations and sub-combinations withone another. The disclosed methods, systems, and apparatus are notlimited to any specific aspect, feature, or combination thereof, nor dothe disclosed methods, systems, and apparatus require that any one ormore specific advantages be present or problems be solved.

Features, integers, characteristics, compounds, chemical moieties, orgroups described in conjunction with a particular aspect, embodiment orexample of the invention are to be understood to be applicable to anyother aspect, embodiment or example described herein unless incompatibletherewith. All of the features disclosed in this specification(including any accompanying claims, abstract, and drawings), and/or allof the steps of any method or process so disclosed, may be combined inany combination, except combinations where at least some of suchfeatures and/or steps are mutually exclusive. The invention is notrestricted to the details of any foregoing embodiments. The inventionextends to any novel one, or any novel combination, of the featuresdisclosed in this specification (including any accompanying claims,abstract, and drawings), or to any novel one, or any novel combination,of the steps of any method or process so disclosed.

It should be appreciated that any patent, publication, or otherdisclosure material, in whole or in part, that is said to beincorporated by reference herein is incorporated herein only to theextent that the incorporated material does not conflict with existingdefinitions, statements, or other disclosure material set forth in thisdisclosure. As such, and to the extent necessary, the disclosure asexplicitly set forth herein supersedes any conflicting materialincorporated herein by reference. Any material, or portion thereof, thatis said to be incorporated by reference herein, but which conflicts withexisting definitions, statements, or other disclosure material set forthherein will only be incorporated to the extent that no conflict arisesbetween that incorporated material and the existing disclosure material.

As used in the specification and the appended claims, the singular forms“a,” “an” and “the” include plural referents unless the context clearlydictates otherwise. Ranges may be expressed herein as from “about” oneparticular value, and/or to “about” another particular value. When sucha range is expressed, another aspect includes from the one particularvalue and/or to the other particular value. Similarly, when values areexpressed as approximations, by use of the antecedent “about,” it willbe understood that the particular value forms another aspect. It will befurther understood that the endpoints of each of the ranges aresignificant both in relation to the other endpoint, and independently ofthe other endpoint. The terms “about” and “approximately” are defined asbeing “close to” as understood by one of ordinary skill in the art. Inone non-embodiment, limiting embodiment the terms are defined to bewithin 10%. In another non-limiting the terms are defined to be within5%. In still another non-limiting embodiment, the terms are defined tobe within 1%.

“Optional” or “optionally” means that the subsequently described eventor circumstance may or may not occur, and that the description includesinstances where said event or circumstance occurs and instances where itdoes not.

Throughout the description and claims of this specification, the word“comprise” and variations of the word, such as “comprising” and“comprises,” means “including but not limited to,” and is not intendedto exclude, for example, other additives, components, integers or steps.“Exemplary” means “an example of” and is not intended to convey anindication of a preferred or ideal aspect. “Such as” is not used in arestrictive sense, but for explanatory purposes.

Certain terminology is used in the following description for convenienceonly and is not limiting. The words “right,” “left,” “lower,” and“upper” designate direction in the drawings to which reference is made.The words “inner” and “outer” refer to directions toward and away from,respectively, the geometric center of the described feature or device.The words “distal” and “proximal” refer to directions taken in contextof the item described and, with regard to the instruments hereindescribed, are typically based on the perspective of the practitionerusing such instrument, with “proximal” indicating a position closer tothe practitioner and “distal” indicating a position further from thepractitioner. The terminology includes the above-listed words,derivatives thereof, and words of similar import.

The thrombectomy devices disclosed herein remove a thrombus using abraided assembly that can be expanded to a diameter of thepractitioner's choosing, enabling the practitioner to custom fit thedevice to the particular vessel and thrombus and during the procedure.Unlike conventional thrombectomy devices, the diameter of the disclosedbraided assembly can be changed mid-procedure as needed. For example,the braided assembly can be opened to a wider diameter to apply moreoutward force against the thrombus should additional grip be needed forits removal. In some embodiments, multiple braided assemblies can beused to address longer thrombi. Each braided assembly can be separatelyexpanded, such that the individual assemblies have different diametersduring the procedure.

The device disclosed herein is used to the remove a thrombus, clot, orplaque from the veins or arteries of the body. It includes an aspirationcatheter and a retrieval device that extends through the lumen of theaspiration catheter. An expandable braided assembly extends over adistal region of the retrieval device, such that when the retrievaldevice exits the distal end of the aspiration catheter, the braidedassembly is positioned outside of the aspiration catheter. An activationwire extends through the lumen of the retrieval device. The distal endof the activation wire exits the retrieval device at an exit point toconnect to and control the expansion of a braided assembly. On theproximal end, the activation wire is attached to a tensioning element.Applying tension to the activation wire causes the braided assembly toexpand to a diameter of the practitioner's choosing. For example, thepractitioner may apply a first level of tension to deploy the braidedassembly to a first, partially expanded configuration and then laterdecide to widen the diameter to the fully expanded configuration byapplying a greater level of tension to the activation wire. The expandedbraided assembly contacts the thrombus, clot, or plaque and is pulledproximally toward the aspiration catheter to assist in removal.Hereinafter the device and methods will be described as removing (orbeing configured to remove) a thrombus. However, it will be understoodthat the device can also be used to remove clots or plaques from thevasculature with no structural (or only slight structural)modifications. Various embodiments of the thrombectomy catheter includea retrieval device with multiple braided assemblies, multiple activationwires, multiple braided sections of a single braided assembly, andretrieval devices with multiple lumens to, for example, enable use witha guidewire.

FIGS. 1A-1D show an embodiment of the thrombectomy device 1. FIG. 1Ashows the aspiration catheter 106, the retrieval device 3, a collapsedbraided assembly 102, and a guidewire tip 103. The aspiration catheter106 is an elongated tube with reinforced construction that allows avacuum to be applied at the proximal end to pull clot and emboli out ofthe artery or vein without collapsing. The aspiration catheter 106 canbe formed of a polymer material. The aspiration catheter 106 can includean imaging marker 8 (such as a fluorescent or radiopaque marker) for usein imaging the position of the catheter during a procedure. Thrombusretrieval device 3 extends through aspiration catheter 106. The braidedassembly 102 extends over a distal region 5 of the retrieval device 3,such that when the retrieval device 3 exits the distal end 7 of theaspiration catheter 106, the braided assembly 102 is positioned outsideof the aspiration catheter 106. In the collapsed configuration, braidedassembly 102 is sized and configured for insertion through theaspiration catheter 106 and into an artery or vein. Guidewire tip 103extends distally from the distal end 107 of the retrieval device 3. Theguidewire tip 103 can be flexible, shapeable, and steerable.

The braided assembly 102 is moveable from a collapsed to an expandedconfiguration. An example of a braided assembly 102 in an expandedconfiguration is shown in FIG. 1B, but the maximum diameter, d_(max), ofthe expanded braided assembly 102 can be changed to any value over acontinuous range, from a fully collapsed diameter, to a partiallyexpanded diameter, to a fully expanded diameter. The maximum diameter ofthe braided assembly, d_(max), is the widest point measuredperpendicular to a longitudinal axis, a, extending through the center ofthe braided assembly 102. The braided assembly 102 can be sized andconfigured to disrupt and capture one or more clots, plaques, and/orthrombi and pull them toward the aspiration catheter 106 where they canbe removed. The braided assembly 102 includes a braid 9, a slidablecollar 108, and a fixed attachment point 101 where the braid 9 anchorsto the retrieval device 3. The braid 9 may be attached directly to theretrieval device 3 at attachment point 101, or the braid 9 may beattached indirectly to the retrieval device 3 at attachment point 101.In some embodiments, the fixed attachment point 101 is a fixed collarthat extends around the retrieval device 3, and the braid is welded,bonded, or otherwise adhered to the fixed collar. Regardless, at thefixed attachment point 101, the braid 9 does not move longitudinallyrelative to the retrieval device 3.

The opposite end of braid 9 is welded, bonded, or otherwise adhered toslidable collar 108. In the embodiments shown, the slidable collar 108is slidably connected to the retrieval device 3 by virtue of its annularshape, which extends circumferentially around the retrieval device 3.The slidable collar 108 slides longitudinally along the retrieval device3 as braid 9 is expanded and collapsed. The slidable collar 108 can bepositioned distally to the fixed attachment point 101 (a distalposition), as shown in FIGS. 1A-1C, or the slidable collar 108 can bepositioned proximally to the fixed attachment point 101 (a proximalposition). In some embodiments, slidable collar 108 or fixed attachmentpoint 101 can include a marker that can be viewed using imagingmodalities during a procedure. For example, the slidable collar 108 orfixed attachment point 101 can include a fluorescent or radiopaquelabel.

The braid 9 is composed of multiple strands of wire. The braid 9 takesan elliptical or a spindle shape when expanded, having a maximumdiameter d_(max) at or near the center of the braid 9 and narrowing asthe braid approaches the fixed attachment point 101 and the slidablecollar 108. The wires are formed of a shape memory material such as, butnot limited to, shape memory polymers or shape memory metals (e.g.,nitinol). The braid 9 has a baseline shape memory of the collapsedconfiguration, which forms a cylindrical structure around the retrievaldevice 3, as shown in FIG. 1A. In the activated, expanded configuration,the braid 9 has a tendency to relax toward the collapsed configuration.

When the practitioner is pulling a thrombus or plaque proximally towardaspiration catheter 106 using braided assembly 102, the braid 9encounters distally oriented drag forces that are strongest along thewidest portions (for example, the central region of the braid adjacentd_(max)) These drag forces resist the proximally oriented pulling forceexerted by the practitioner. The distal end of braid 9 at slidablecollar 108 will encounter less drag force while being pulled proximallybecause the radial force it exerts on the radially adjacent vasculatureor thrombus is small, negligible, or non-existent. If the braid is notproperly designed, the sliding collar 108 and distal end of the braid 9will invert into the wider, central regions of the braid 9. Inversionduring the procedure can be prevented by optimizing factors such as thepic count (crosses per inch), the wire diameter, the number of wires,and the ply of the braid (sets of overlapping braids). Higher pic countsincrease flexibility, while lower pic counts increase longitudinalstiffness. Likewise, a braid with more than one ply (multiple sets ofbraids nested within each other), will be stiffer than a single-plybraid. Braids can be one-ply, two-ply, three-ply, or more. Braids withmore wires will be stiffer than those with fewer wires, and braids withwider diameter wires will be stiffer than those with narrow diameterwires. Wires of varying diameters can be used within the same braid 9.

The design of the braided assemblies 102 disclosed herein may vary basedon whether the device 1 is intended for an arterial procedure or for avenous procedure, since the procedure site will be wider in a venoussetting. For example, a braid 9 designed for a venous application mayhave a d_(max) of from about 0.8 inches to 1.2 inches, including about0.8 inches, about 0.9 inches, about 1.0 inch, about 1.1 inches, andabout 1.2 inches. For venous applications, a braid 9 may have a wirediameter range from about 0.005 inches to about 0.02 inches, including0.005 inches, 0.0075 inches, 0.01 inches, 0.0125 inches, 0.015 inches,0.0175 inches, and 0.02 inches. Different wires of the braid 9 may havedifferent diameters, or they may have the same diameter. In some venousembodiments, the diameters of the wires of the braid 9 are 0.01 inches,0.0125 inches, and/or 0.015 inches. Two-ply braids can utilize smallerwire diameters without sacrificing the radial force that can be applied.The pic count can be from 2 to 6 for venous applications. In someembodiments used in venous applications, the pic count is 3, 4, or 5.The number of wires per braid for a venous application can be anywherefrom 8 to 40, including 8, 16, 24, 32, and 40.

Braids for venous applications were tested using a selection of theabove listed venous application parameters. End points included theexpansion force and the radial outward force applied by the braid to theinner surface of a tubing that simulates a vein (the tubing having aninner diameter of 24 millimeters). The expansion force is the forcerequired to open the braid, as applied to the activation wire. The datais shown below in Table 1.

TABLE 1 Prototype testing for braids used in venous applications WireMaximum Radial Outward Diameter Braid OD Force in 24 mm ExpansionPrototype Braid Ply (Inches) # of Wires (inches) ID tube (N) force (N) ADouble 0.008 16 per ply 1.0 4.4 2.5 (32 total) B Double 0.010 16 per ply1.0 5.5-6.6 6 (32 total) C Single 0.0125 24 1.0 8.6-9.9 10

For arterial applications, the braid 9 can have d_(max) of from about0.1 inches to about 0.4, including about 0.1 inches, about 0.12 inches,about 0.14 inches, about 0.18 inches, about 0.2 inches, about 0.22inches, about 0.24 inches, about 0.28 inches, about 0.3 inches, about0.32 inches, about 0.34 inches, about 0.36 inches, about 0.38 inches andabout 0.4 inches. For example, the braid 9 can have a d_(max) of about0.28 inches, 0.3 inches, or 0.31 inches. The diameter of the wires ofthe braid 9 for an arterial application can range from about 0.001inches to about 0.007 inches, including about 0.001 inches, about 0.002inches, about 0.003 inches, about 0.004 inches, about 0.005 inches,about 0.006 inches, and about 0.007 inches. Different wires of the braid9 may have different diameters, or they may have the same diameter. Insome arterial embodiments, the diameters of the wires of braid 9 are0.003 inches, 0.004 inches and/or 0.005 inches. Two-ply braids canutilize smaller wire diameters without sacrificing the radial force thatcan be applied. The pic count can be from 5 to 30 for arterialapplications, including a pic count of 5, 6, 7, 8, 9, 10, 11, 12, 13,14, 15, 16, 117, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 and 30.In some embodiments used in arterial applications, the pic count is 10,12, or 15. The number of wires per braid 9 for an arterial applicationcan be anywhere from 8 to 54, including 8, 16, 24, 32, 40, 48, and 54.In some embodiments, the number of wires per braid 9 for an arterialapplication is 26, 24, or 30.

Braids for arterial applications were tested using a selection of theabove listed arterial application parameters. End points included theradial outward force applied by the braid to the inner surface of atubing (the tubing having an inner diameter of 6 millimeters), and theproximal force needed to pull the braid through a restriction in thetubing (the inner diameter of the restriction being 4 millimeters). Thetubing and the restriction simulate an artery and a thrombus/plaque,respectively. Favorable prototypes give a high radial outward forcewithout requiring excessive force to pull the braid through therestriction. The data is shown below in Table 2. All braids tested wereone-ply.

TABLE 2 Prototype testing for braids used in arterial applicationsProfile (Distal Radial Outward Force to pull Wire bond Maximum Forceapplied to through 4 mm ID Diameter Pic # of OD) Braid OD 6 mm I.D.tubing Restriction Prototype (inches) count Wires (inches) (inches)(Newtons) (Newtons) A 0.004 10 16 0.050 0.28 0.8 1.8 B 0.004 15 24 0.0530.28 1.0 2.8 C 0.005 10 16 0.054 0.31 1.5 3.2 D 0.005 10 24 0.058 0.311.6 4.1 E 0.006 10 16 0.060 0.31 1.7 4.4 F 0.006 12 16 0.063 0.30 1.84.6 G 0.002 24 48 0.073 0.31 0.8 1.9 H 0.003 24 48 0.078 0.31 1.8 3.5 I0.004 12 24 0.054 0.31 1.9 2.6

The activation wire 105 extends through the lumen of the retrievaldevice 3, exits the retrieval device 3 at exit point 11, and extendsdistally along the exterior surface of the retrieval device 3. Thedistal end 13 of the activation wire 105 is attached to slidable collar108. As such, the activation wire 105 is able to control the expansionand collapse of the braid 9 via the slidable collar 108. The distancebetween exit point 11 and slidable collar 108 affects the length thatthe slidable collar can be pulled along retrieval device 3 to open thebraided assembly 102. If it is too close to slidable collar, the braidedassembly 102 will not be able to open fully. As such, exit point 11should be positioned proximally far enough from the unexpanded positionof slidable collar 108 to enable the braided assembly 102 to open to itsmaximum outer diameter. FIG. 1C shows the embodiment of FIGS. 1A and 1Bwithout braid 9 to facilitate viewing the activation wire 105 and theactivation wire exit point 11. FIG. 1D is a cross sectional view ofactivation wire 105 in retrieval device 3, taken at line A-A of FIG. 1C.The internal positioning of the proximal regions of the activation wire105 (within retrieval device 3) is advantageous in that no friction orbulk is added by the system that controls expansion of the braidedassembly 102.

The proximal region of activation wire 105 (not shown) may be tensionedand released to control the expansion and collapse of the braidedassembly 102 via movement of slidable collar 108. Under tension, theactivation wire 105 moves proximally within the lumen of the retrievaldevice 3 as it translates the tension from the proximal region of theactivation wire 105 to the braided assembly 102. In implementationswhere the slidable collar 108 is in the distal position (as shown), theexit point 11 of the activation wire is located proximally to theslidable collar 108. The exit point 11 can be, for example, a portal inthe sidewall of retrieval device 3. Use of a slidable collar 108 toexpand the braided assembly 102 is advantageous because the distal endof the braided assembly 102 can be moved while the distal region 5 ofthe retrieval device 3 maintains a constant position within thevasculature. Maintaining a constant position of the distal region 5 ofretrieval device 3 is advantageous because sliding proximal/distalmovement of the distal region 5 within the vessel can result in vesseldamage or perforation.

In implementations where the slidable collar 108 is in the proximalposition relative to the fixed attachment point (not shown), theactivation wire 105 extends distally past the slidable collar 108 insidethe retrieval device 3, exits the retrieval device 3 at exit point 11,then doubles back and extends along the exterior surface of theretrieval device 3 to attach to the proximally located slidable collar108. The exit point 11 can be a portal in the sidewall of the retrievaldevice as described above, or the exit point 11 can be the distal end107 of the retrieval device 3.

Retrieval device 3 can include a proximal hypotube 100 and a distalsupport tube 104, as shown in FIG. 1C. In some embodiments, the hypotube100 extends through the support tube 104. However, the distal region canbe made more flexible by attaching the proximal end of the distalsupport tube 104 to the distal end 17 of the proximal hypotube 100 (forexample, by adhesive bonding, heat bonding, or welding processes). Thefixed attachment point 101 of the braided assembly 102 can be located ondistal support tube 104 and the slidable collar 108 can extend aroundthe distal support tube 104, such that the braided assembly 102 ispositioned over and around the distal support tube 104. The braidedassembly 102 can alternatively be positioned only partially over thedistal support tube (i.e., one of the fixed attachment point 101 or theslidable collar 108 is attached to the proximal hypotube 100, and theother of the fixed attachment point or the slidable collar 108 isattached to the distal support tube 104). In some embodiments, thesupport tube 104 serves to increase the overall diameter of theretrieval device 3, for example, to accommodate a larger diameter braidand to encapsulate the guidewire tip 103. The distal support tube 104can also provide a lower friction surface for movement of the slidablecollar 108 than the proximal hypotube 100 would provide.

In some embodiments, distal support tube 104 has greater flexibilitythan the proximal hypotube 100. For example, the distal support tube 104can be made of a polymer material, while the proximal hypotube 100 ismade of a more rigid metal material. In some embodiments, the proximalhypotube 100 is constructed from metal hypodermic needle tubing. Thehypotube 100 can be up to 50 times stiffer than the support tube 104.There are several advantages to having a distal support tube 104 withgreater flexibility than proximal hypotube 100. The greater flexibilityof the support tube 104 enables a gradual transition in flexibilitybetween the hypotube 100 and the guidewire tip 103. In some scenarios,the greater flexibility of the distal support tube 104 can facilitatemovement of the braided assembly 102 through a tortuous thrombus. Thegreater flexibility can promote kink resistance. The greater flexibilityof the distal support tube 104 can also facilitate the introduction of aportal or exit point 11 during the production of the device. The higherrigidity of the hypotube 100 (as compared to support tube 104) isimportant because it allows the retrieval device 3 to be pushed throughthe vasculature. The rigidity of hypotube 100 also helps to ensure thatthe braided assembly 102 can be pushed through a thrombus or plaque.

On the proximal end, the activation wire 105 can be attached to atensioning element (not shown) that allows the activation wire 105 to bemoved forward or retracted backward within the retrieval device 3.Applying tension to the activation wire 105 causes the slidable collar108 to move and causes the braided assembly 102 to expand to a diameterof the practitioner's choosing. Similarly, releasing tension on theactivation wire 105 allows the braided assembly 102 to relax into thecollapsed, baseline configuration.

In some embodiments, such as the one shown in FIG. 2 , the deviceincludes a proximal handle 128. The handle 128 is coupled to a proximalend of retrieval device 3. The tensioning element is a knob 129 that iscoupled to the proximal end of activation wire 105 on the inside of thehandle. Actuation of the knob 129 in one direction causes the activationwire 105 to be tensioned (expanding the braided assembly), and actuationof the knob 129 in the opposite direction releases tension on theactivation wire 105 (collapsing the braided assembly). In otherembodiments, the tensioning element can include a slider, rachetingmechanism, or lever. The aspiration catheter 106 terminates in ay-adaptor (not shown) that separates the lumen of the aspirationcatheter to be connected to a vacuum source for removal of the clot oremboli and allows the activation wire to be connected to the handle 128.

Another embodiment of a proximal handle 128 is shown in FIGS. 7A-7C. Thehandle 128 of FIGS. 7A-7C is advantageous in that it enables apractitioner to lock the braided assembly 102 at a fixed outer diameter.This can be useful, for example, when pushing and pulling the devicethrough a thrombus. As shown in FIG. 7A, proximal handle 128 is coupledto a proximal end of retrieval device 3. Activation wire 105 extendsproximally past the proximal end retrieval device 3 and into proximalhandle 128. Strain relief section 139 is formed of a flexible materialthat prevents kinking of the retrieval device 3 just distal to thehandle 128. Proximal handle 128 also includes a tensioning element inthe form of locking slider 136, which slides proximally and distallywithin groove 138 and can be locked in place to secure the outerdiameter of the braided assembly 102 during a procedure. The undersideof locking slider 136 and groove 138 is shown in FIG. 7B, and a crosssectional view of locking slider and groove 138 is shown in FIG. 7C.Locking slider 136 includes a sliding portion 146 and a lock button 148.As seen in FIG. 7B, downward pointing teeth 140 extend downward from theinner surface 133 of the outer casing 135 of handle 128, from a positionadjacent the groove 138. The lock button 148 includes an exteriorportion 141 with a textured gripping surface. The lock button 148extends downward through sliding portion 146, and includes an interiorportion 137. The interior portion 137 of the lock button 148 extendsaway from the exterior portion 141 of lock button 148 in a directionthat is perpendicular to the longitudinal axis A-A of the locking slider136. Interior portion 137 includes upward facing teeth 142 that areconfigured to engage with the downward facing teeth 140 of the outercasing 135 of the handle 136. Spring 150, which is vertically positionedwithin slider 146, beneath the exterior surface 141 of lock button 148,exerts an upward force on lock button 148 to hold the upward facingteeth 142 in a locked configuration with the downward facing teeth 140of the outer casing 135. When lock button 148 is compressed, the spring150 is compressed and the teeth 140, 142 disengage. With the lock button148 pressed and the teeth 140, 142 disengaged, proximal or distal forcecan be applied to sliding portion 146 to move the locking slider 136within the groove 138. An interior portion 144 of the sliding portion146 grips the activation wire 105. As the locking slider 136 is movedwithin groove 138, the activation wire 105 is moved proximally ordistally to affect the expansion or allow the collapse of the braidedassembly 102.

Conventional thrombectomy devices utilize shape memory elements with abaseline expanded configuration. These conventional devices riskinadvertent overexpansion and damage to the vessel. Furthermore,conventional devices are often restrained by a bulky overlying sheath,which is pulled back to allow the device to self-expand.

Advantageously, using a device with a shape memory of the collapsedposition reduces the risk of overexpansion and injury duringself-expansion. Self-collapse also allows the device to be restrainedusing the low-profile activation wire system described herein. Anadditional advantage is the ability to expand the braided assembly tovarious diameters to precisely custom fit the size of the vessel. Thiscan be especially useful if the size of the vessel is different thanoriginally anticipated. The level of grip between the braid 9 and thesurrounding thrombus can also be customized as needed by applyingdifferent levels of tension to the activation wire 105. For example, thepractitioner may apply a first level of tension to deploy the braidedassembly 102 to a first expanded outer diameter to contact the thrombus.If the force between the thrombus and the braid 9 is not enough to pullthe thrombus toward the aspiration catheter 106, the practitioner canwiden the braid 9 to a second expanded outer diameter by applying agreater second level of tension to the activation wire 105. This wideneddiameter provides a greater contact force between the thrombus and thebraid 9, such that the thrombus can be more easily pulled towardaspiration catheter 106.

FIGS. 3A-3D show an additional embodiment of a thrombectomy devicehaving a braided assembly 19 with multiple braided sections 111, 112.The elongated nature of this embodiment facilitates the capture andretrieval of long thrombi. As shown in FIG. 3A and FIG. 3B, ach of thebraided sections 111, 112 is attached to and extends around the distalregion 22 of retrieval device 21. The braided assembly 19 includesmultiple sliding collars 23, 25 and a fixed attachment point 27.Proximal braided section 111 is attached to and extends between thefixed attachment point 27 and the proximal slidable collar 23, where itis welded, bonded, or otherwise adhered at a central sliding attachmentpoint 29. Distal braided section 112 is attached to and extends betweenthe proximal slidable collar 23 and the distal slidable collar 25. Insome embodiments, the braided sections are formed by constraining onelarger braid with the proximal slidable collar 23. In other embodiments,each braided section is formed from a separate braid (such that each ofthe proximal and distal braided assemblies are separately fixedlyattached to proximal slidable collar 23). In some embodiments, theslidable collars 23, 25 can be positioned distally to the fixedattachment point 27, as illustrated in FIG. 3A. In other embodiments,the slidable collars can be positioned proximally to the fixedattachment point (not shown). Though illustrated with two braidedsections 111, 112, other embodiments of the braided assembly 19 couldinclude more than two braided sections and more than two slidablecollars.

FIG. 3C shows the thrombectomy device of FIGS. 3A and 3B without thebraided assembly 19. Retrieval device 21 has a hypotube 131 fixedlyattached to a support tube 130. A single activation wire 132 extendsthrough hypotube 131 and support tube 130 to an exit point 134positioned on the support tube 130. From there, it travels along theouter surface of support tube 130, running beneath proximal slidingcollar 23 to attach to distal sliding collar 25. Cross sectional viewsshown in FIG. 3D, FIG. 3E, FIG. 3F, and FIG. 3G show the radial positionof activation wire 132 with respect to hypotube 131, the support tube130, and the guidewire tip 103 at various axial locations along thethrombectomy device shown in FIG. 3C. The activation wire 132 isutilized to control expansion of the braided assembly via connection tothe distal sliding collar 25. In other embodiments, the activation wire132 can be attached to the proximal sliding collar 23. retrieval deviceProximal movement of the proximal slidable collar 23 or the distalslidable collar 25 by the activation wire generates a force on the otherof the two slidable collars, such that the two braided sections 111, 112are expanded (or partially expanded) in unison. As described above, thebraids are formed of a shape memory material with a bias toward thecollapsed configuration, so that tensioning the activation wire enablesmultiple levels of expansion.

FIG. 4 shows an additional embodiment with multiple, separatelyexpandable braided assemblies 37, 39. The braided assemblies 37, 39 arespaced from each other along the distal region 32 of retrieval device31. The proximal braided assembly 37 includes braided section 113 thatextends between a fixed attachment point 33 and a slidable collar 115.The distal braided assembly 39 includes braided section 114 that extendsbetween a fixed attachment point 35 and a slidable collar 116. Eachbraided assembly is controlled by a separate activation wire, such thateach braided assembly can be individually controlled. Each activationwire exits the retrieval device 31 from an exit point beneath theindividual braid and attaches to the individual slidable collar (notshown). The multiple activation wires can travel through the same lumenin retrieval device 31, or they could have individual lumens. Dependingupon the positioning of the slidable collars in relation to the fixedattachment points, in some embodiments, each additional activation wirecan travel through the same lumen and exit the retrieval device at thesame portal, or at different portals. In some embodiments, one or moreactivation wires can exit from the distal end of the retrieval device31.

As with the previously described embodiments, the braids of theembodiment shown in FIG. 4 are formed of a shape memory material with abias toward the collapsed configuration, such that tensioning theactivation wire enables deployment of the braid to a range of diameters.Each braided assembly is deployable to a partially expandedconfiguration by placing a first level of tension in the attachedactivation wire, or to a fully expanded configuration by placing asecond, greater level of tension into the activation wire. Thus, whenmultiple activation wires and braided assemblies are used, a firstbraided assembly can be deployed to a partially expanded state while asecond braided assembly is deployed in a fully expanded state. In somescenarios, it may be advantageous for one braided assembly to be fullycollapsed while another braided assembly is either partially or fullyexpanded. This can be advantageous, for example, when pulling a longerthrombus into the aspiration catheter 106. The proximal braided section113 can be collapsed as it enters the aspiration catheter, prior to thedistal braided section 114 which is still outside of the aspirationcatheter.

In some embodiments, braids of separate braided sections or separatebraided assemblies can have different properties, such as differentmaximum expanded diameters, different wire sizes, different wiredensities, different numbers of wires, etc. These properties can varydepending upon the positioning of the braided section or the braidedassembly along the retrieval device. For example, the distal braidedsection or braided assembly might have a larger expanded diameter tobetter pull back against the thrombus, while the proximal braidedsection(s) or braided assembly(s) might be less dense and stronger tobetter engage the middle of the thrombus.

FIGS. 5A-5C show an embodiment of the thrombectomy device that enablesuse with a guidewire, such that a practitioner can remove and reinsertthe device to the same anatomic position multiple times (for example, toclean the device during the procedure). FIG. 5A shows aspirationcatheter 127, retrieval device 121, guidewire tubing 118, braidedassembly 123 (in the collapsed configuration), and guidewire 45.Guidewire tubing 118 is positioned around the distal region 61 ofretrieval device 121. The guidewire tubing 118 is shorter than theretrieval device 121 in the longitudinal direction, such that theguidewire 45 leaves the guidewire tubing 118 at the proximal guidewireexit 117 and extends alongside retrieval device in a proximal direction.FIG. 5B shows the embodiment of FIG. 5A with the braided assembly 123 inan expanded state. As shown in the cross section of FIG. 5C taken atline B-B of FIG. 5B, guidewire 45 extends through the first lumen 124 ofthe guidewire tubing 118. The guidewire 45 exits guidewire tubing 118 atdistal guidewire exit 47. The guidewire tubing 118 can include a distalatraumatic tip 120. The guidewire tubing 118 can be formed, for example,of a polymer material. Retrieval device 121, including activation wire125, extends through a second lumen 126 of the guidewire tubing 118. Asdescribed above, the activation wire 125 is connected on the proximalend to a tensioning element, extends through retrieval device 121 to anexit point, leaves the retrieval device 121 at the exit point (beneaththe braid), and attaches at its distal end to the slidable distal collar122 on the braided assembly 123. The exit point can be, for example, atunnel through the sidewalls of the retrieval device 121 and theguidewire tubing 118 (i.e., a tunnel formed by a portal in the sidewallof the retrieval device 121 that is aligned/coaxial with a portal in thesidewall of the guidewire tubing 118). In use, the guidewire tubing 118and the retrieval device 121 are introduced together over the previouslyplaced vascular guidewire 45. Because the guidewire 45 is retainedwithin the guidewire tubing 118, it is pulled at least partially to theside within the lumen of aspiration catheter 127 and can move withoutinterfering with activation wire 125. The guidewire tubing 118 and theretrieval device 121 keep the activation wire 125 and the guidewire 45moving in an axial direction, independently from one another, using alow-profile and low-friction design. Once in position, the braidedassembly 123 is expanded and the proximal end of the aspiration catheter127 is connected to a vacuum source. The braided assembly 123 isexpanded and then retracted back toward the aspiration catheter 127,pulling the clot with it and breaking it into small pieces.

Methods of performing thrombectomy procedures are also disclosed herein.An example method is illustrated in FIGS. 6A-6F. FIG. 6A illustratesthrombus 49 occluding vessel 51. Distal end of aspiration catheter 53 isadvanced through the vasculature to an area proximal to the thrombus 49,as shown in FIG. 6B. The distal end of retrieval device 55 carryingbraided assembly 57 is advanced out the distal end of the aspirationcatheter 53 and through thrombus 49, such that the braided assembly 57is distal to thrombus 49, as shown in FIG. 6C. The practitioner thenplaces tension in the activation wire housed inside the retrieval device55, thereby moving the activation wire longitudinally within the lumenof the retrieval device and moving the slidable collar of the braidedassembly longitudinally over the exterior surface of the retrievaldevice. Movement of the slidable collar via the activation wire causesbraided assembly 57 to expand to the diameter of the practitioner'schoosing. Should the practitioner wish to alter the level of expansionduring the procedure (i.e., change the maximum diameter d of the braidedassembly 57), this is made possible by altering the level of tension inthe activation wire, which again moves the activation wire within theretrieval device and moves the slidable collar, as described above.Advantageously, the distal end of the retrieval device 55 maintains astationary position as the braided assembly is expanded to the optimaldiameter. Maintaining a constant position of the distal end of retrievaldevice 55 is advantageous because sliding proximal/distal movement ofthe distal end within the vessel can result in vessel damage orperforation.

FIG. 6D shows the braided assembly 57 in an expanded configuration,sized to fit the vessel 51. The practitioner then pulls the retrievaldevice 55 proximally and contacts the thrombus 49 with the braidedassembly 57, as shown in FIG. 6E. The thrombus 49 and braided assembly57 are pulled proximally toward aspiration catheter 53. The aspirationcatheter 53 can be connected to an external vacuum source (not shown),which enables the aspiration of the thrombus 49 into the distal end ofthe aspiration catheter 53. The aspiration catheter 53 is then retractedproximally, as illustrated in FIG. 6F, and removed from the body.

The ability to open the braided assembly to a range of differentdiameters is useful to thrombectomy procedures for multiple reasons andin multiple scenarios. The ability to custom fit the braid to aparticular vessel during the procedure is preferable over introducing abraid that expands to a predetermined size, then discoveringmid-procedure that it is either too small to grip the thrombus or thatit is too large and has damaged the vessel. As another exemplaryadvantage, the level of grip between the braid and the thrombus can beoptimized mid-procedure. For example, the practitioner may apply a firstlevel of tension to the activation wire to deploy the braided assemblyto a first expanded outer diameter to contact the thrombus. If the forcebetween the thrombus and the braid is not sufficient to pull thethrombus toward the aspiration catheter, the practitioner can widen thebraid to a second expanded outer diameter by applying a greater secondlevel of tension to the activation wire. This widened diameter increasesthe contact force between the thrombus and the braid, such that thethrombus is more easily pulled toward aspiration catheter.

The methods can also be performed using a guidewire. For example, theguidewire can be positioned distal to the thrombus prior to advancingthe distal end of the retrieval device. The retrieval device extends atleast partially through a lumen of the guidewire tubing, such as in theembodiment of FIGS. 5A-5C. Together, the retrieval device and guidewiretubing are advanced over the guidewire and toward the thrombus. Theguidewire extends through a separate lumen of the guidewire tubing thanthe retrieval device and activation wire. Once positioned, theactivation wire is moved longitudinally within the retrieval device toexpand the braided assembly.

Long thrombi can be addressed using braided assemblies with multiplebraided sections such as the embodiment shown in FIG. 3 . Movement ofthe slidable collar results in expansion of more than one of the braidedsections, resulting in a relatively long braided assembly. In someembodiments a device with multiple, separately expandable braidedassemblies, such as the one shown in FIG. 4 , can be used to treat longthrombi. With separately expandable braided assemblies, as the thrombusis drawn proximally closer to the distal end of the aspiration catheter,the proximally positioned braided assembly collapses from a firstexpanded outer diameter to the collapsed diameter (or to a narrowersecond expanded outer diameter). The distally positioned braidedassembly maintains an expanded outer diameter that is greater than theouter diameter of the proximally positioned braided assembly until ittoo is pulled into the aspiration catheter.

Various implementations of the thrombectomy device and its correspondingcomponents are formed from one or more biocompatible materials, such ascobalt chromium, titanium and titanium alloys, stainless steel, nitinol,platinum, gold, or other metals, as well as ceramics or polymers. Inaddition, in some implementations, the thrombectomy device or portionsthereof includes a coated material.

1-35. (canceled)
 36. A method of performing a thrombectomy procedure,the method comprising: advancing a distal end of an aspiration catheterthrough the vasculature to an area proximal to a thrombus; advancing adistal end of a retrieval device carrying at least one braided assemblyout of the distal end of the aspiration catheter and to a positionadjacent to the thrombus; tensioning an activation member that extendsthrough the retrieval device and securely attaches to a first end regionof a braided assembly; pulling the first end region toward a second endregion of the braided assembly with the activation member, therebyexpanding a braid that extends between the first end region of thebraided assembly and the second end region of the braided assembly;contacting the thrombus with the braid; adjusting a level of tension inthe activation member, thereby adjusting a level of grip between thebraid and the thrombus; retracting the thrombus proximally toward thedistal end of the aspiration catheter using the braided assembly; andaspirating the thrombus into the distal end of the aspiration catheter.37. The method of claim 36, wherein advancing a distal end of aretrieval device comprises positioning the braided assembly at aposition distal to the thrombus.
 38. The method of claim 36, whereinadjusting the level of tension in the activation member comprises movingthe activation member longitudinally within a lumen of the retrievaldevice.
 39. The method of claim 36, wherein adjusting the level oftension in the activation member moves the first end region of thebraided assembly longitudinally relative to the second end region of thebraided assembly.
 40. The method of claim 36, wherein adjusting thelevel of tension in the activation member changes an expanded outerdiameter of the braided assembly.
 41. The method of claim 36, whereinadjusting the level of tension in the activation member comprisesincreasing the level of tension in the activation member.
 42. The methodof claim 41, wherein increasing the level of tension comprises pullingthe activation member proximally within a lumen of the retrieval device.43. The method of claim 42, wherein increasing the level of tensiondecreases a distance between the first end region of the braidedassembly and the second end region of the braided assembly.
 44. Themethod of claim 41, wherein increasing the level of tension increases anouter diameter of the braid to increase the level of grip between thebraid and the thrombus.
 45. The method of claim 36, wherein the braidedassembly has a shape memory bias toward a collapsed configuration. 46.The method of claim 45, wherein adjusting the level of tension comprisesreleasing tension in the activation member, thereby allowing the braidedassembly to at least partially collapse.
 47. The method of claim 36,further comprising locking the braided assembly in a fixed outerdiameter.
 48. The method of claim 47, further comprising retracting thebraided assembly while it is locked in the fixed outer diameter.
 49. Themethod of claim 47, wherein locking the braided assembly in the fixedouter diameter comprises using a locking slider to prevent longitudinalmovement of the activation member.
 50. The method of claim 49, whereinusing the locking slider comprises forcing a first set of teeth intoengagement with a second set of teeth.
 51. The method of claim 49,wherein adjusting the level of tension in the activation membercomprises unlocking the braided assembly to permit longitudinal movementof the activation member.
 52. The method of claim 51, wherein unlockingthe braided assembly comprises using the locking slider to disengage afirst set of teeth from a second set of teeth.
 53. The method of claim36, wherein expanding the braided assembly causes the braided assemblyto take a spindle shape.
 54. The method of claim 36, wherein retractingthe thrombus comprises breaking the thrombus into pieces.